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| United States Patent |
5,126,069
|
|
Kud
, et al.
|
June 30, 1992
|
Water-soluble or -dispersible, oxidized polymer detergent additives
Abstract
A detergent composition contains as essential ingredients surfactants and
from 0.1 to 15% by weight of water-soluble or -dispersible polymers
obtainable by oxidation of polymers containing not less than 10 mol % of
carboxyl-containing monoethylenically unsaturated monomers as
copolymerized units and having Fikentscher K values of from 8 to 300.
| Inventors:
|
Kud; Alexander (Eppelsheim, DE);
Baur; Richard (Mutterstadt, DE);
Funhoff; Angelika (Heidelberg, DE);
Denzinger; Walter (Speyer, DE);
Hartmann; Heinrich (Limburgerhof, DE);
Raubenheimer; Hans-Juergen (Ketsch, DE)
|
| Assignee:
|
BASF Aktiengesellschaft (Ludwigshafen, DE)
|
| Appl. No.:
|
596325 |
| Filed:
|
October 12, 1990 |
Foreign Application Priority Data
| Current U.S. Class: |
510/476; 510/315; 510/318; 510/361 |
| Intern'l Class: |
C11D 001/00 |
| Field of Search: |
252/174.23,DIG. 2,95,DIG. 11
|
References Cited
U.S. Patent Documents
| 3637609 | Jan., 1972 | Blumberg et al. | 525/366.
|
| 3691139 | Sep., 1972 | Blumbergs et al. | 260/78.
|
| 3755264 | Aug., 1973 | Testa | 525/327.
|
| 3853781 | Dec., 1974 | Haschke et al. | 252/132.
|
| 3887480 | Jun., 1975 | Rue et al. | 252/135.
|
| 3922230 | Nov., 1975 | Lamberti et al. | 252/174.
|
| Foreign Patent Documents |
| 0025551 | Mar., 1981 | EP.
| |
| 0075820 | Apr., 1983 | EP.
| |
| 0404377 | Apr., 1990 | EP.
| |
| 2388834 | Nov., 1978 | FR.
| |
Primary Examiner: Lieberman; Paul
Assistant Examiner: DiNunzio; M.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt
Claims
We claim:
1. A detergent composition containing as essential constituents
(1) one or more anionic surfactants, one or more nonionic surfactants or a
mixture thereof and
(2) from 0.1 to 15% by weight based on the weight of the formulation of a
water-soluble or -dispersible polymer prepared by oxidation of the
preformed polymer, said preformed polymer containing not less than 10 mol
% of carboxyl-containing monoethylenically unsaturated monomers as
copolymerized units prior to oxidation and having K values of from 8 to
300 (determined by the method of H. Fikentscher in aqueous solution at
25.degree. C. and pH 7 on the sodium salt of the polymer at a
concentration of 1% by weight).
2. A detergent composition as claimed in claim 1, wherein constituent (2)
is a homopolymer or copolymer of acrylic acid, methacrylic acid, maleic
acid or itaconic acid of K 10-150 which has been oxidized in an aqueous
medium.
3. A detergent composition as claimed in claim 1 or 2, wherein the polymer
used as constituent (2) is obtained by oxidation with 2-50% by weight of
peroxide, hydroperoxide, peracid, perester, hydrogen peroxide, halogen,
nitric acid, hypochlorite, perborate, percarbonate, persulfate or a
mixture thereof.
4. A detergent composition as claimed in claim 1, wherein the polymer used
as constituent (2) is obtained by oxidizing with a mixture of a
percompound and a redox catalyst.
5. The detergent composition of claim 1, wherein the polymer used as
constituent (2) is obtained by oxidation with an oxidizing agent which
releases oxygen on being heated alone or in the presence of catalysts.
Description
Detergents, as will be known, contain not only surfactants but also
builders. Builders have many functions in detergent formulations. For
instance, they are intended to augment the soil detaching action of the
surfactants; render the hardness of the water harmless, whether by
sequestration of the alkaline earth metal ions or by dispersing the
hardness products precipitated from the water; promote the dispersion and
stabilization of the colloidal soil particles in the wash liquor; and act
as buffers to maintain the most suitable pH during the wash. In solid
detergent formulations, builders are also intended to make a positive
contribution to a satisfactory powder structure and free-flow properties.
Phosphate-based builders are very efficient at the above-described tasks.
Consequently, pentasodium triphosphate was for a long time the
unchallenged builder of choice in detergent compositions. However, the
phosphates present in detergents pass virtually unchanged into the
effluent. Since phosphates are an excellent nutrient for aquatic plants
and algae, they are responsible for the eutrophication of lakes and slow
water courses.
Water treatment installations without a third treatment stage for the
specific precipitation of phosphates are not sufficiently effective in
removing phosphates. For this reason there has long been a search under
way for something to take the place of phosphate builders in detergents.
In the meantime, water-insoluble ion exchange materials based on zeolites
have found their way in phosphate-free or low-phosphate detergents.
However, owing to their specific properties zeolites are incapable of
replacing phosphate builders alone. They are augmented in their activity
by other detergent additives comprising carboxyl-containing compounds,
such as citric acid, tartaric acid, nitrilotriacetic acid and in
particular polymeric carboxyl-containing compounds and salts thereof. Of
the last group of compounds mentioned, the homopolymers of acrylic acid
and the copolymers of acrylic acid and maleic acid have particular
importance as detergent additives; cf. U.S. Pat. No. 3,922,230 and EP
Patent 25,551. The incrustation inhibitors used are in particular
homopolymers of acrylic acid and copolymers of maleic acid and acrylic
acid having molecular weights of about 50,000-120,000. However, these
polymers are not capable of augmenting the removal of particulate soil
(e.g. clay, kaolin, soot) or the dispersal thereof in washing liquors.
Suitable for this purpose are in particular low molecular weight
polyacrylic acids which in turn, however, are poor incrustation
inhibitors.
It is an object of the present invention to provide a polymer suitable for
use in detergent compositions which is not only an effective incrustation
inhibitor but also an effective dispersant of particulate soil.
We have found that this object is achieved according to the present
invention by using a water-soluble or -dispersible polymer obtainable by
oxidation of a polymer which contains not less than 10 mol % of
carboxyl-containing ethylenically unsaturated monomers as copolymerized
units and has K values of from 8 to 300 (determined by the method of H.
Fikentscher in aqueous solution at 25.degree. C. and pH 7 on the sodium
salt of the polymer at a concentration of 1% by weight) as an additive in
detergent compositions in an amount of from 0.1 to 15% by weight, based on
the particular formulation.
To obtain the detergent additives to be used according to the present
invention, carboxyl-containing polymers which contain not less than 10 mol
% of carboxyl-containing ethylenically unsaturated monomers as
copolymerized units and which are water-soluble or -dispersible at least
in the form of the salts are oxidized. To prepare the carboxyl-containing
polymers, the monomers of group (a) are subjected to polymerization either
alone or mixed. Suitable group (a) monomers are for example
monoethylenically unsaturated monocarboxylic acids having from 3 to 8
carbon atoms and monoethylenically unsaturated dicarboxylic acids having
from 4 to 8 carbon atoms in the molecule. Examples of these compounds are
acrylic acid, methacrylic acid, vinylacetic acid, allylacetic acid,
propylideneacetic acid, ethylenepropionic acid, ethylidenepropionic acid,
dimethylacrylic acid, ethylacrylic acid, crotonic acid, maleic acid,
fumaric acid, itaconic acid, methaconic acid, methylenemalonic acid,
citraconic acid, and also salts or, if existent, anhydrides thereof. These
monomers are polymerized either to homopolymers or to copolymers.
The monomers of group (a) may also be copolymerized with the monomers of
group (b). The monomers of group (b) are carboxyl-free ethylenically
unsaturated compounds. The resulting copolymers are water-soluble or
-dispersible at least in the form of the alkali metal or ammonium salts.
Preferred monomers of group (b) are the esters, amides and nitriles of the
carboxylic acids mentioned under (a). Preferred compounds of these classes
are for example methyl acrylate, ethyl acrylate, methyl methacrylate,
ethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylates,
hydroxybutyl acrylates, hydroxyethyl methacrylate, hydroxypropyl
methacrylates, hydroxybutyl methacrylates, dimethylaminoethyl acrylate,
dimethylaminoethyl methacrylate, diethylaminoethyl acrylate,
diethylaminoethyl methacrylate, acrylamide, methacrylamide and also
N-alkylacrylamides and N-alkylmethacrylamides having from 1 to 18 carbon
atoms in the alkyl moiety. Examples thereof are N-dimethylacrylamide,
tert.-butylacrylamide, the monoamides and diamides of maleic acid,
dimethylaminopropyl methacrylamide, acrylamidoglycolic acid, acrylonitrile
and methacrylonitrile. The copolymers with basic monomers are preferably
used in the form of the salts with mineral acids, such as hydrochloric
acid or sulfuric acid, or in quaternized form. Suitable quaternizing
agents are for example dimethyl sulfate, diethyl sulfate, methyl chloride,
ethyl chloride and benzyl chloride. The monomers of group (b) serve to
modify the polymers of the monomers of group (a). The monomers of group
(b) never account for more than 90 mol % of a copolymer. It is of course
possible to use mixtures of monomers of group (b) together with monomers
of group (a) in the copolymerization and copolymerize for example a
mixture of acrylic acid, methyl acrylate and hydroxypropyl acrylate.
A further modification of the carboxyl-containing polymers may be effected
by carrying out the polymerization of the monomers of group (a) with or
without monomers of group (b) in the presence of monomers of group (c).
This group includes for example sulfo-containing monomers, such as
vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid,
styrenesulfonic acid, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate
and acrylamidomethylpropanesulfonic acid, and phosphono-containing
monomers, for example vinyl phosphonate, allyl phosphonate and
acrylamidomethylpropanephosphonic acid. It is also possible to use as
monomers of group (c) N-vinylpyrrolidone, N-vinylcaprolactam,
N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide,
N-vinyl-N-methylacetamide, N-vinylimidazole, N-vinylmethylimidazole,
N-vinyl-2-methylimidazoline, vinyl acetate, vinyl propionate, vinyl
butyrate, styrene, olefins of from 2 to 10 carbon atoms, such as ethylene,
propylene, isobutylene, hexene and diisobutene, and vinyl alkyl ethers,
such as methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether,
isobutyl vinyl ether, hexyl vinyl ether and octyl vinyl ether, and
mixtures thereof. The copolymers of the ethylenically unsaturated monomers
which contain carboxylic acid, sulfonic acid and phosphonic acid groups
may be subjected to the oxidation in the form of the free acids or in a
partially or completely neutralized form. Neutralization is preferably
effected using alkali metal bases, such as sodium hydroxide solution and
potassium hydroxide solution, ammonia or amines, such as trimethylamine,
ethanolamine or triethanolamine. The monomers of group (c) may be
copolymerized with the monomers of group (a) and optionally the monomers
of group (b) either alone or mixed with one another. The modified monomers
of group (c), if used at all, never account for more than 90 mol %,
preferably 10-50 mol %, of the copolymer.
The copolymers may additionally contain as copolymerized units a further
class of monomers of group (d), which are monomers having two or more
ethylenically unsaturated double bonds, these double bonds being
nonconjugated. Suitable compounds of group (d) are for example
methylenebisacrylamide, N,N-divinylethyleneurea, N,N-divinylpropyleneurea,
ethylidene bis-3-vinylpyrrolidone and esters of polyhydric alcohols such
as glycol, butanediol, glycerol, pentaerythritol, glucose, fructose,
sucrose, polyalkylene glycols of a molecular weight of 400 to 6000 and
polyglycerols of molecular weight 126-268 with acrylic acid, methacrylic
acid, maleic acid and fumaric acid using per mole of alcohol used at least
2 mol of one of the carboxylic acids mentioned or else a mixture of the
carboxylic acids mentioned. Further suitable monomers of group (d) are for
example divinylbenzene, divinyldioxane, divinyl adipate, divinyl
phthalate, pentaerythritol triallyl ether, pentaallylsucrose, diallyl
ethers and divinyl ethers of polyalkylene glycols of molecular weight
400-6000, ethylene glycol divinyl ether, butanediol divinyl ether and
hexanediol divinyl ether. The modifier monomers of group (d), if used at
all, never account for more than 5 mol % of the copolymer.
Particular preference for use in detergent formulations is given to
reaction products which are obtainable by oxidizing homopolymers and
copolymers of acrylic acid, methacrylic acid, maleic acid, fumaric acid
and itaconic acid. The carboxyl-containing polymers subjected to oxidation
have K values of from 8 to 300, preferably from 10 to 150. These K values
are determined by the method of H Fikentscher in aqueous solution at
25.degree. C. and pH 7, in each case on the sodium salt of the polymer at
a concentration of 1% by weight.
Suitable oxidizing agents are those which release oxygen on being heated
alone or in the presence of catalysts. Suitable organic compounds are in
general peroxides, which eliminate active oxygen very readily. At low
temperatures only hydroperoxides and peracids have a significant oxidizing
effect; peresters, diacyl peroxides and dialkyl peroxides become active
only at higher temperatures.
Suitable peroxides are for example diacetyl peroxide, isopropyl
percarbonate, tert.-butyl hydroperoxide, cumene hydroperoxide,
acetylacetone peroxide, methyl ethyl ketone peroxide, di-tert.-butyl
peroxide, dicumyl peroxide, tert.-butyl perpivalate, tert.-butyl
peroctanoate and tert.-butyl perethylhexanoate. Preference is given to the
inexpensive inorganic oxidizing agents which are suitable in particular
for oxidizing aqueous solutions of the carboxyl-containing polymers.
Examples which may be mentioned are chlorine, bromine, iodine, nitric
acid, sodium permanganate, potassium chlorate, sodium hypochlorite, sodium
perborate, sodium percarbonate and sodium persulfate. A particularly
preferred oxidizing agent is hydrogen peroxide. The decomposition of the
percompounds, i.e. the oxidation, can be speeded up by the addition of
accelerants or activators. Such mixtures of percompounds and accelerants
are customarily used in the polymerization of monomers as redox catalysts.
The accelerants or activators are reducing but slightly electron-releasing
substances such as, for example, tert.-amines, sulfinic acids,
dithionites, sulfites, .alpha.- and .beta.-ketocarboxylic acids, glucose
derivatives and heavy metals, preferably in the form of soluble salts of
inorganic or organic acids or complexes. Specific examples are
dimethylaniline, dimethyl-p-toluidine, diethylaniline, sodium dithionite,
sodium sulfite, ascorbic acid, glucose, pentaacetylglucose, ferroammonium
sulfate, copper chloride and the acetylacetonates of iron, copper, cobalt,
chromium, manganese, nickel and vanadium.
The oxidizing agents are added, based on the polymers, in amounts of from 2
to 50% by weight, preferably from 5 to 30% by weight. The reducing agents
are used, calculated on the oxidizing agents, in amounts of from 2 to 50%
by weight. The heavy metal compounds are used, calculated as heavy metal
and based on the polymer, in amounts of from 0.1 to 100 ppm, preferably
from 0.5 to 10 ppm. It is frequently of advantage to add to the
percompounds not only reducing agents but also heavy metal compounds to
speed up the reaction in particular if it is carried out at low
temperatures. The reaction temperatures can vary from 20.degree. C. to
150.degree. C., preferably from 50.degree. C. to 120.degree. C. It is also
advantageous on occasion to speed up the oxidation by irradiation with UV
light, or else to oxidize at low temperatures and for a short time, in
particular if only the --S-- groups in the polymer are to be oxidized
without a decrease in the K value. It is also possible to use air and
oxygen alone or combined with oxidizing agents.
Those polymers with a high K value are strongly degraded in the course of
the oxidation, while low molecular weight polymers are degraded only to a
relatively small degree. The degree of degradation of the polymers in the
course of the oxidation is easy to determine by comparing the K values of
unoxidized polymer with the K value of the oxidized polymer. For example,
a sodium polyacrylate of K value 90 is oxidized by 10% of hydrogen
peroxide and 8 hours, heating at 98.degree. C. to a K value of 28. By
contrast, a sodium polyacrylate of K value 28 subjected to the same
reaction conditions will at the end of the oxidation have a K value of 23.
To oxidize the carboxyl-containing polymers, the oxidizing agents are made
to act either on the pulverulent polymers directly or on suspensions of
the polymers in an inert medium or on solutions in inert solvents.
Suitable solvents for the polymers are for example methanol, ethanol,
n-propanol, isopropanol, water and solvent mixtures which contain water.
Preferably, the oxidation is carried out in aqueous polymer solutions or
dispersions. The oxidation of carboxyl-containing polymers results not
only in a reduction of the molecular weights of the polymers but also in
the oxidation of functional groups, for example S groups, which are formed
in the course of the polymerization of monomers (a) with or without
monomers (b) to (d) in the presence of mercapto compounds as regulators.
Suitable mercapto compounds are for example mercaptoethanol,
mercaptopropanols, mercaptobutanols, mercaptoacetic acid,
mercaptopropionic acid, mercaptobutyric acid, n-butylmercaptan,
tert.-butylmercaptan and dodecylmercaptan.
The carboxyl-containing polymers obtainable by oxidation are excellent
additives for detergents. They are remarkable in that, compared with the
unoxidized carboxyl-containing polymers, they show an unexpectedly
improved calcium carbonate dispersing capacity and exhibit a high
stability in detergents containing oxidizing agents. In
chlorine-containing detergents, for example, they are more stable than the
unoxidized polymers. The carboxyl-containing polymers obtainable by
oxidation are used in amounts of from 0.1 to 15, preferably from 0.5 to
10, % by weight as additives in detergents, based on the detergent
formulation. These formulations may be pulverulent or else liquid.
Detergent formulations are customarily based on surfactants with or
without builders. In pure liquid detergents, the use of builders is
usually dispensed with. Suitable surfactants are for example anionic
surfactants, such as C.sub.8 -C.sub.12 -alkylbenzenesulfonates, C.sub.12
-C.sub.16 -alkanesulfonates, C.sub.12 -C.sub.16 -alkyl sulfates, C.sub.12
-C.sub.16 -alkyl sulfosuccinates and sulfated ethoxylated C.sub.12
-C.sub.16 -alkanols, and also nonionic surfactants, such as C.sub.8
-C.sub.12 -alkylphenol ethoxylates, C.sub.12 -C.sub.20 -alkanol
alkoxylates and also block copolymers of ethylene oxide and propylene
oxide. The end groups of the polyalkylene oxides may be capped, meaning
that the free OH groups of the polyalkylene oxides may be etherified,
esterified, acetalized and/or aminated. A further possible modification is
to react the free OH groups of the polyalkylene oxides with isocyanates.
The nonionic surfactants also include C.sub.4 -C.sub.18 -alkylglucosides
and the alkoxylated products obtainable therefrom, in particular those
preparable by reaction of alkylglucosides with ethylene oxide. The
surfactants usable in detergents may also have a zwitterionic character
and be soaps. The surfactants are in general present in detergent
compositions in an amount of from 2 to 50, preferably from 5 to 45% by
weight.
Detergent builders are for example phosphates, e.g. orthophosphate,
pyrophosphate and especially pentasodium triphosphate, zeolites, sodium
carbonate, polycarboxylic acids, nitrilotriacetic acid, citric acid,
tartaric acid, the salts of said acids and also monomeric, oligomeric or
polymeric phosphonates. The individual substances are used in the
detergent formulations in varying amounts, for example sodium carbonate in
amounts of up to 80%, phosphates in amounts of up to 45%, zeolites in
amounts of up to 40%, nitrilotriacetic acid and phosphonates in amounts of
up to 10% and polycarboxylic acids in amounts of up to 20%, each
percentage being based on the weight of the substances and on the
detergent formulation as a whole. Owing to the environmental damage caused
by the use of phosphates, the level of phosphates in detergent
compositions is increasingly reduced, so that present-day detergents
contain not more than 25% of phosphate or are phosphate-free.
The oxidized polymers can also be used in liquid detergents. Liquid
detergent blends customarily contain liquid surfactants or alternatively
solid surfactants which are soluble or at least dispersible in the
detergent blend. Suitable surfactants for this purpose are products which
are also used in pulverulent detergents and also liquid polyalkylene
oxides or polyalkoxylated compounds.
Detergent formulations may also contain corrosion inhibitors, such as
silicates. Suitable silicates are for example sodium silicate, sodium
disilicate and sodium metasilicate. Corrosion inhibitors can be present in
the detergent formulation in amounts of up to 25% by weight. Further
customary additives for detergent formulations are bleaching agents, which
may be present therein in an amount of up to 30% by weight. Suitable
bleaching agents are for example perborates and chlorine-releasing
compounds, such as chloroisocyanurates. Another group of additives which
may be present in detergents are grayness inhibitors. Known substances of
this kind are carboxymethylcellulose, methylcellulose,
hydroxypropylmethylcellulose and graft polymers of vinyl acetate on
polyalkylene oxides of molecular weight 1000-15,000. Grayness inhibitors
may be present in the detergent formulation in amounts of up to 5%.
Further customary but optional additives for detergents are fluorescent
whitening agents, enzymes and scents. Pulverulent detergents may also
contain up to 50% by weight of a strength standardizing diluent, such as
sodium sulfate. Detergent formulations may be free of water or contain
small amounts, for example up to 10% by weight, of water. Liquid
detergents customarily contain up to 80 % by weight of water. Customary
detergent formulations are described in detail for example in
DE-A-3,514,364, which is hereby expressly incorporated herein by
reference.
The K values of the polymers were determined by the method of H.
Fikentscher, Cellulose Chemie 13 (1932), 58-64, 71-74. Note that
K=k.times.10.sup.3. The measurements were carried out on 1% strength
aqueous solutions of the sodium salts of the polymers at 25.degree. C. and
pH 7. Unless otherwise stated, the % ages are by weight.
EXAMPLES
Preparation of oxidized polymers
Polymer 1
500 g of a 35% strength aqueous solution of a copolymer of K 91 formed from
maleic acid and vinyl methyl ether in a molar ratio of 1:1 and 95%
neutralized with sodium hydroxide were heated to about 95.degree. C. 117 g
of a 30% strength aqueous solution of hydrogen peroxide were metered in at
a uniform rate over 8 hours. This is followed by a further 2 hours of
heating and then cooling. Following the oxidation the K value of the
polymer was 22.
Polymer 2
1500 g of 36% strength aqueous solution of a polyacrylic aid of K 99 were
heated to a slow boil at 100.degree. C. 175 g of a 30% strength aqueous
hydrogen peroxide solution were metered in at a uniform rate over 8 hours.
Thereafter the reaction mixture was cooled. It had a solids content of
32%. The K value of the oxidized polyacrylic acid was 67.
Polymer 3
750 g of a sodium polyacrylate of K 28 prepared using 4.5% of
2-mercaptoethanol (calculated on acrylic acid used) were heated to
95.degree. C. in the form of a 45% strength solution in water, and 226 g
of a 30% strength aqueous hydrogen peroxide solution were added in the
course of 8 hours. Subsequently the reaction mixture was heated for a
further 4 hours and then cooled down. The solids content of the polymer
solution was 42%. The oxidized polymer had a K value of 26.
Polymer 4
1.2 kg of a 40% strength aqueous solution of a copolymer of K 64 formed
from 70% of acrylic acid and 30% of maleic acid and 90% neutralized with
sodium hydroxide were heated in a stirred autoclave to 110.degree. C.
under super-atmospheric pressure. 358 g of a 30% strength aqueous hydrogen
peroxide solution were metered in continuously over 8 hours. The polymer
solution obtained was then cooled down. The solids content of the aqueous
solution was 30%. The oxidized polymer had a K value of 19.
Polymer 5
1.5 kg of a 40% strength aqueous solution of a copolymer of K 64 formed
from 70% of acrylic acid and 30% of maleic acid and 90% neutralized with
sodium hydroxide were admixed with a suspension of 60 g of sodium
perborate in 240 g of water, and the mixture was heated at 100.degree. C.
under superatmospheric pressure for 4 hours. The solution was then cooled
down. It had a solids content of 36%. The K value of the oxidized polymer
was 49.
Polymer 6
500 g of a poly(sodium acrylate) of K 21 prepared using 8% of
2-mercaptoacetic acid (calculated on acrylic acid used) were admixed in
the form of a 46% strength aqueous solution with 1 ml of a 0.1% strength
aqueous copper(II) chloride solution, and the mixture was heated to
50.degree. C. A solution of 37.6 g of 30% strength hydrogen peroxide and
50 g of water were added over 4 hours, and subsequently the reaction
mixture was heated for a further hour before being cooled down. The
aqueous solution had a solids content of 45%. The oxidized homopolymer had
a K value of 20.
Polymer 7
1200 g of a 40% strength aqueous solution of the sodium salt of a copolymer
of K 60 formed from 70% of acrylic acid and 30% of maleic acid were
admixed with 4.8 g of a 0.1% strength copper(II) chloride solution, and
the mixture was heated to 80.degree. C. As soon as that temperature was
reached, 288 g of 50% strength hydrogen peroxide and a solution of 9.6 g
of sodium disulfite and 70.4 g of water were added at a uniform rate over
8 hours, and subsequently the reaction mixture was heated at 80.degree.
C. for a further hour. This gave a solution of an oxidized polymer having
a solids content of 30%. The K value of the oxidized polymer was 15.
Polymer 8
1000 g of a 40% strength aqueous solution of the sodium salt of a copolymer
of K 60 formed from 70% of acrylic acid and 30% of maleic acid were
admixed with 14 g of a 0.1% strength iron(II) ammonium sulfate solution,
and the mixture was heated to the boil. 134 g of a 30% strength hydrogen
peroxide solution were added to the boiling mixture over 8 hours, and the
mixture was subsequently heated at the boil for a further hour before
being cooled down. The solids content of the polymer solution was 36%. The
oxidized polymer had a K value of 27.
Polymer 9
1000 g of a 40% strength aqueous solution of the sodium salt of a copolymer
of K 60 formed from 70% of acrylic acid and 30% of maleic acid were heated
to the boil and admixed in the course of 8 hours, at a uniform rate, with
134 g of a 30% strength aqueous hydrogen peroxide solution and a solution
of 8 g of ascorbic acid in 50 g of water. Thereafter the reaction mixture
was heated at the boil for a further hour. This gave a solution of an
oxidized copolymer having a solids content of 36%. The K value of the
oxidized copolymer was 28.
Polymer 10
30 g of a polyacrylate of K 29 prepared using 4.5% by weight of
3-mercaptopropionic acid (calculated on acrylic acid used) were admixed in
the form of a 53% strength aqueous solution with 0.02 ml of a 0.01%
strength aqueous solution of iron(II) ammonium sulfate and 2.65 g of 30%
strength hydrogen peroxide. This solution was heated to 90.degree. C. and
left at that temperature for 10 hours. On cooling, the solution was found
to have a solids content of 43.7%. The oxidized homopolymer had a K value
of 29.
Polymer 11
1000 g of a 40% strength aqueous solution of the sodium salt of a copolymer
of K 50 formed from 50% of acrylic acid and 50% of maleic acid were heated
to the boil under atmospheric pressure and admixed over 8 hours at a
uniform rate with 240 g of 50% strength hydrogen peroxide. After all the
hydrogen peroxide had been added, the reaction mixture was heated at the
boil for a further hour. The aqueous solution had a solids content of 32%.
The oxidized copolymer had a K value of 14.
Polymer 12
1500 g of a 34% strength aqueous solution of a commercial sodium
polyacrylate of K 80 were heated to 98.degree. C. under atmospheric
pressure and admixed at the stated temperature with 308 g of a 50%
strength aqueous hydrogen peroxide solution in the course of 24 hours. The
reaction mixture was then cooled down. It had a solids content of 28%. The
K value of the oxidized homopolymer was 16.
Polymer 13 (Comparison)
Sodium polyacrylate of K 15 obtainable by solution polymerization of
acrylic acid in water using 12% of 2-mercaptoethanol.
Polymer 14 (Comparison)
Sodium polyacrylate of K 40 obtainable by solution polymerization of
acrylic acid in water using 3 % of 2-mercaptoethanol.
Polymer 15 (Comparison)
Sodium polyacrylate of K 20 obtainable by solution polymerization of
acrylic acid in water using 8% of 2-mercaptoacetic acid.
Polymer 16 (Comparison)
Sodium salt of a commercial copolymer of K 60 formed from 70% of acrylic
acid and 30% of maleic acid.
Polymer 17 (Comparison)
Sodium salt of a commercial copolymer of K 50 formed from 50% of acrylic
acid and 50% of maleic acid.
APPLICATION EXAMPLES
To test the incrustation inhibiting effect of the above-described oxidized
polymers, each polymer was incorporated into two different pulverulent
detergents A and B. Each of these washing powder formulations was used to
wash test fabrics made of cotton terry towelling. The number of wash
cycles was 15. Following this number of washes, each fabric was ashed to
determine its ash content. The lower the ash content of the test fabric,
the greater the effectiveness of the polymer ingredient of the washing
powder, reported as a percentage where 0% effectiveness denotes the
highest possible ash content or incrustation buildup without additive in
the washing powder and 100% effectiveness denotes complete prevention of
any deposit by the incrustation inhibitor. Following the 15 wash cycles,
the terry towelling had an ash content of 2.5% in the case of washing
powder A and 2.38% in the case of washing powder B.
______________________________________
Experimental conditions for determining incrustation:
______________________________________
Apparatus: Launder-O-Meter from Atlas,
Chicago
Number of wash cycles:
15
Wash liquor: 250 g, the water used containing
4 mmol of hardness per liter
(molar ratio of calcium to
magnesium equal to 3:1)
Length of wash: 30 min at 60.degree. C. (including heating-
up time)
Detergent dosage:
8 g/l
Terry towelling cloth:
20 g
Washing powder A (phosphate-free)
12.5% of dodecylbenzenesulfonate (50%)
4.7% of C.sub.13 /C.sub.15 -oxo process alcohol polyglycol ether
containing 7 ethylene oxide units
2.8% of soap
25% of zeolite A
12% of sodium carbonate
4% of sodium disilicate
1% of magnesium silicate
20% of sodium perborate
10% of copolymer
0.6% of sodium carboxymethylcellulose
remainder to 100%: sodium sulfate
Washing powder B (reduced phosphate)
12.5% of dodecylbenzenesulfonate (50%)
4.7% of C.sub.13 /C.sub.15 oxo process alcohol polyglycol ether
containing 7 ethylene oxide units
2.8% of soap
9.25% of pentasodium triphosphate
0.7% of sodium diphosphate
0.05% of sodium orthophosphate
24% of zeolite A
4% of sodium disilicate
1% of Mg silicate
20% of sodium perborate
3% of polymer
remainder to 100%: sodium sulfate
______________________________________
Table 1 shows the effectiveness of the oxidized polymers of varying K.
Table 2 shows the effectiveness of the unoxidized polymers.
TABLE 1
______________________________________
Effectiveness
Effectiveness
(%) on terry
(%) on terry
Example
Polymer towelling
towelling
No. No. K value Powder A Powder B
______________________________________
1 12 16.1 83.2 47.4
2 6 19 86.5 69.1
3 8 27 82.4 81.3
4 3 25.5 -- 78.3
______________________________________
TABLE 2
______________________________________
Compara- Effectiveness
Effectiveness
tive (%) on terry
(%) on terry
Example Polymer towelling
towelling
No. No. K value Powder A Powder B
______________________________________
1 13 15.0 73.4 29.1
2 14 38.0 84.1 76.9
3 15 20.0 81.6 52.2
4 16 60.0 86.4 84.3
______________________________________
Tables 1 and 2 reveal that the oxidized homopolymers of acrylic acid are
more effective incrustation inhibitors than the unoxidized homopolymers of
similar K and hence similar molecular weight. It is also evident that the
oxidized copolymer of acrylic acid is not less effective than the
unoxidized copolymer although the K value of the oxidized copolymer is
distinctly lower than that of the unoxidized copolymer.
Clay dispersion
The removal of particulate soil from fabric surfaces is augmented by the
addition of polyelectrolytes. The stabilization of the dispersion formed
by the detached particles is an important function of these
polyelectrolytes. The stabilizing effect of anionic dispersants is due to
the fact that the adsorption of dispersant molecules on the surfaces of
the solids increases their surface charge and the repellence. Further
variables determining the stability of the dispersion include, inter alia,
steric effects, temperature, the pH and the electrolyte concentration.
The following clay dispersion (CD) test provides a simple way of assessing
the dispersing power of various polyelectrolytes:
CD test
The particulate soil model used is a finely ground china clay SPS 151. 1 g
of clay is thoroughly dispersed in 98 ml of water in a 100 ml measuring
cylinder in the presence of 1 ml of a 0.1% strength sodium salt solution
of the polyelectrolyte for 10 minutes. Immediately after the stirring has
ended a sample of 2.5 ml is taken from the center of the measuring
cylinder, diluted with water to 25 ml and placed in a turbidimeter to
determine the turbidity. Further samples of the dispersion are taken after
30 and 60 minutes and measured. The turbidity of the dispersion is
reported in NTUs (nephelometric turbidity units). The lower the rate of
sedimentation of the dispersion during storage, the higher the measured
turbidities and the stabler the dispersion.
The second physical variable determined is the dispersion constant .tau.,
which describes the time course of the sedimentation process. Since the
sedimentation process can be described to an approximation by a
mono-exponential time law, .tau. indicates the time at which the turbidity
has dropped to the 1/e-th part of the original state at time t=0. The
higher the .tau., the slower the rate of sedimentation of the dispersion.
Determination of the calcium carbonate dispersing capacity (CCDC)
The calcium carbonate dispersing capacity (CCDC) is determined by
dissolving 1 g of the polymer in 100 ml of distilled water, neutralizing
if necessary by adding 1 g of sodium hydroxide solution, and adding 10 ml
of 10% strength sodium carbonate solution. The solution is then titrated
with 0.25M calcium acetate solution while the pH and the temperature are
kept constant. The pH is set by adding either dilute sodium hydroxide
solution or dilute hydrochloric acid solution. The dispersing capacity is
determined at 20.degree. C. and pH 11 and at 80.degree. C. and pH 10. The
results are reported in Table 3.
TABLE 3
__________________________________________________________________________
Clay dispersion test
__________________________________________________________________________
Ex-
ample
Polymer
Turbidity
After
storage
Dispersion
CCDC at
No. No. at once
30 min
60 min
constant
20.degree. C.
80.degree. C.
__________________________________________________________________________
5 4 680 590 570 211.3 210 480
6 5 640 520 450 144.5 325 295
7 8 670 580 520 208.0 265 210
8 9 690 550 540 132.3 260 175
9 13 720 620 600 200.6 245 230
10 3 680 600 550 239.7 125 140
__________________________________________________________________________
Com-
para-
tive Polymer
Turbidity
After
storage
Dispersion
Example
No. at once
30 min
60 min
constant
20.degree. C.
80.degree. C.
__________________________________________________________________________
5 16 640 470 380 97.2 250 275
6 17 670 530 460 128.0 360 355
7 15 700 590 530 175.5 95 40
__________________________________________________________________________
The turbidity is given in nephelometric turbidity units and the calcium
carbonate dispersing capacity (CCDC) in mg of calcium carbonate per g of
polymer sodium salt.
The oxidatively degraded homopolymers and copolymers of acrylic acid of
Examples 5 to 10 are much better clay dispersants than the unoxidized
starting compounds (Comparative Examples 5 to 7).
This is found on comparing the measured turbidities (the higher the
measured value, the better the dispersion) and on considering the
dispersion constants. They are distinctly higher than those of the
comparative compounds, which indicates a distinct increase in the
stability of the dispersion. In addition, the CCDC values are partly
improved or at least, despite the oxidative degradation, of the same order
of magnitude as those of the untreated homopolymers or copolymers. If
Example 8 is compared with the unoxidized starting material (Comparative
Example 6), it is seen that, again, oxidation has brought about a distinct
improvement in clay dispersion with a slight decrease in the CCDC,
although the CCDC still falls well within the range of highly effective
incrustation inhibitors.
Determination of the stability of hypochlorite-containing formulations
Hypochlorite-containing formulations are destabilized by low molecular
weight polyacrylic acids, and release chlorine. To determine the
destabilizing effect, 4 g of polysodium acrylate are dissolved in 100 ml
of a formulation containing 1% of active chlorine and the solution is
stored at 55.degree. C. for 7 days. Thereafter the residual level of
active chlorine is determined iodometrically.
TABLE 4
______________________________________
Active chlorine content in %
immediate after storage
Example Polymer (relative, based on the
No. No. immediate value)
______________________________________
11 10 99 60.4
______________________________________
Active chlorine content in
% immediate after storage
Comparative
Polymer (relative, based on the
Example No. immediate value)
______________________________________
8 13 65 22.4
9 14 91 44.3
10 15 73 31.4
______________________________________
On comparing Example 11 with the unoxidized polymers of Comparative
Examples 8-10, it is found that oxidation brings about a distinct
improvement in the stability of the active chlorine in
hypochlorite-containing formulations.
The oxidized homopolymers and copolymers of acrylic acid are not only
efficient incrustation inhibitors but also excellent dispersants for
particulate soil.
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